MODX Revolution PHP Snippet to return site_start context setting of b.com context

gistfile1.txt

<?php
// assumes there is a site_url context_setting for b.com with a value such as http://b.com/
$setting = $modx->getObject('modContextSetting', array(
 'context_key' => 'b.com',
 'key' => 'site_url',
 ));  
return $setting->get('value');